High-frequency connectors are used in cable ends, package feedthroughs, adaptors, probes, and similar applications. Connector interfaces typically provide a single coaxial structure that maintains the characteristic impedance of the transmission line through the connector. Balanced techniques, which use two high-frequency transmission lines, are desirable in some applications because they can provide a larger signal and superior noise immunity compared to unbalanced techniques, but generally involve making twice as many connections to a device or circuit.
Balanced cables are presently available with two coaxial cables that are joined within a single cable housing for most of the length of the cable, but these balanced cables are basically two coaxial cables with regular coaxial cable ends. Joining the cables together for most of their length avoids some inter-cable movement and keeps the cables reasonably balanced, but connecting the cables to a device requires connecting each of the cable ends causing relative movement between the cable ends that can introduce measurement error or uncertainty. Other presently available types of balanced cables extend center conductors of two coaxial transmission lines through a single connector without maintaining the coaxial structures of the transmission lines through the connector. While these types of balanced cables are typically used at low frequencies (e.g. below 200 MHz), they are not well suited for use in high-frequency applications.